An approximately 11-year-old neutered male Chihuahua was evaluated seven hours after being attacked by a larger dog. The dog had been transferred from a local emergency clinic after its condition had been stabilized. On physical examination, the dog had a 5-cm laceration on the left body wall, with subcutaneous fat and the head of the spleen protruding. A few other smaller lacerations were also evident. Abdominal radiographs were obtained.

Which of the following is the most likely cause of the large, curved gas-fluid opacity interface dorsal to the thoracic vertebral column on the lateral projection?

a) A gas-filled, displaced stomach

b) A displaced left caudal lung lobe

c) Subcutaneous emphysema

d) A large abscess